Cryogenic drilling of KevlarTM composite laminates

Arabic Abstract

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English Abstract

Cryogenic machining is gaining increasing acceptance in metal industries and is replacing the conventional machining processes to overcome the shortcomings of the conventional coolants. Materials like aramid fibre reinforced composite are difficult to machine because of the unique combination of physical properties of fibre and the matrix. The present study evaluates the machinability of KevlarTM-49 composite laminates at low temperatures using TiN coated HSS drill. The effects of workpiece temperature and cutting conditions on machinability of laminates were assessed using drilling thrust force, cutting torque, specific energy and hole quality. Both workpiece temperature and machining conditions were found to influence each of maximum thrust force, maximum torque and specific cutting energy at different levels. Both drilling thrust and torque showed increasing trend with decrease in the workpiece temperature under all machining conditions. Drilled hole patterns of the laminates obtained using optical technique showed less fibre protrusion and elamination at low temperatures compared to ambient. An improvement of about 400% was observed when the workpiece temperature was reduced from 20℃ to -120℃.